Backfire on deceleration

[lynn02]

Today was the first day I could really wind my CRF100 out. I noticed on deceleration it would backfire. What is causing it to backfire?

 

[biglou]

A couple pops on decel is ok. If it's cracking like a machine gun, you may need to turn out the pilot screw (richer), or go up on the pilot jet.

Check out this thread for some more info: http://www.dirtrider.net/forums3/showthread.php?t=92314&referrerid=19516

 

[MikeBronn]

A couple pops on decel is ok. If it's cracking like a machine gun, you may need to turn out the pilot screw (richer), or go up on the pilot jet.

Exact same problem my son had on his XR-100. He noticed that "POP!" coming out of the muffler occasionally (not every time) when he was decellerating after accelerating for a while. (mainly when he topped it out in 4th or 5th gear) He richened the jetting slightly and it fixed the problem as we knew it, since he commented that he didnt notice this happen since.

 

[lynn02]

Mine is doing as MikeBronn explained. Can someone tell me where the pilot screw is? Thanks for the help. :thumb:

 

[Jasle]

its on the side of the carb. one is bigger with a knurled surface and that should be idle. the small one is the pilot screw. If it is on the left then turn it out if it is on the right turn it in.

 

[Andy Thistleton]

Pilot air screw should be turned out to one and a half turns to may be two if ur just *****ing about with the baby :joke:

Thats over here in the UK!
Not too sure if its more over there because the air and humidity is different!